1. Field of the Invention
This invention relates broadly to cold-seal adhesives, packages sealed therewith and new methods of forming packages. More particularly, it concerns latex (emulsion) adhesives capable of forming dry adhesive layers on plastic or equivalent film that can then later be pressure bonded together, without the use of heat, to form wrappers about candy or other comestibles.
2. Description of the Prior Art
It is conventional practice to form packages for many products simply by wrapping the product in paper, metal foil, plastic film or other sheet material. Often, in order to complete the packaging, overlapped layers of the wrapper are bonded together in some way, e.g., by crimping, stabling, cementing, etc.
The bonding of sheet wrappers by cementing overlapped layers with some type of adhesive is attractive from the viewpoint of cost savings and package esthetics. However, this can be restrictive as to the choice of the wrapper material if suitable adhesives do not exist for the bonding of certain classes of sheet material. For example, some types of plastic films, such as polyolefin film, are difficult to permanently bond together with adhesive because adhesives to not stick easily to such films.
Also, the type of product being packaged can limit the choice of wrapper material and adhesive. For example, candy and other comestibles require government approved wrapper materials and adhesive ingredients which eliminates many materials available for packaging other type products. Moreover, heat sensitivity of some candy and other comestibles mitigate against the use of heat in effecting the sealing of wrappers about them. Hence, use of cold-seal adhesives, i.e., adhesives that can cement together layers of sheet material without need to apply heat thereto (see U.S. Pat. No. 4,375,383), is extensively used in the wrapper packaging of candy bars and the like.
The present invention provides new improvements in cold-seal adhesives that are particularly useful in the packaging of candy and other comestibles.